Yesterday evening, we received a link from long time reader The Dog Father, which directed us towards a new review of the Vertex Lumina LED light. You can find the document which cites its authors as J. Behzad and A. Schneider here [PDF]. Note that the file is hosted by Vertex–the hosting of the file [...]
Yesterday evening, we received a link from long time reader The Dog Father, which directed us towards a new review of the Vertex Lumina LED light. You can find the document which cites its authors as J. Behzad and A. Schneider here [PDF]. Note that the file is hosted by Vertex–the hosting of the file as well as the highly specific nature of the report raise question if this examination and review was done independently. I’d guess it was not. Keep this in mind for any and all equipment reviews. I am also hesitant to use the word review to describe this article–it is more justification and support for the Lumina’s LED design than any review aquarists are accustomed to reading.
All that said, we now have some confirmation of past reported features and additional specifics on the Vertex Lumina LED light:
- Onboard computer controls each LED module wirelessly (based on IEEE 802.15.4 PHY)
- LCD screen, 4 buttons
- Default, Custom and Expert modes–Expert enables real time, complete control via PC & V-link USB
- Each module has 3 colors: White, Blue (470nm) and Royal Blue (450nm)
- 16 LEDs (8W, 4B, 4 RB) @ 40w max
- Modules can be swapped out for additional color options (i.e. red)
- Large aluminum heatisink body, with a “heat channel” and fans to keep operating temperatures low
The review is quite detailed. I would argue too detailed. In fact, I fear the greek-smeared paper will be too intimidating for most aquarists to take the time to read, digest and analyze. I admit, having read this just last night, I have not had the time to digest and settle all my thoughts. However some surprises and omissions have already caught my attention. I’d like to preface my opinions in that, I am basing this off of just the review which, given the nature of this particular review, is not a reflection of the Vertex Lumina LED light. Rather, my questions are based around support Behzad and Schneider provide for the design of the Vertex Lumina. I would also say I applaud Vertex for taking a different approach–right or wrong, if they bring a new option to the table that is different than what is currently available and they defend their ideas–hats off to them.
Lastly, no contact information or credentials have been given on the document. Hopefully Vertex, Behzad and Schneider will be ready to engage in conversation with aquarists on this–as this ‘review’ will certainly spark debate.
The review dives into the serious discussion of LED optics with:
While most vendors of LED fixtures ship their parts with LED optics to focus the light to an extreme spot where very high PAR values are achieved, Vertex decided to walk the way differently. The target was to get as much light as possible into the tank and concurrently achieve a flat light distribution to satisfy all animals wherever they are located.
Omitting the actual calculations and Snell walkthrough, the writers offer up some math to theoretically show that using a specific height and an LED with a beam angle of 124 degrees (bare emitter) that no “stray light” would leave the tank–that is the refraction of the light from the water and tank sides would direct it to your light hungry corals, and sand bed, and rocks. They go on to say:
Fixtures that use LED optics claim they use this for more penetration, to have more PAR for example on the sand bed. However usually people that have corals on the sand bed are not too worried about light intensity because these are low light demanding corals. Those people that have SPS, or light demanding corals want to put the coral closer to the surface of the water so they get more light.
With optics closer to the water surface the diameter of the light spread circles are smaller, that means while there are a lot of light in that little spot, the dead spots in the shallower depths are even more than what is on the sand bed, however people don’t see this because these is no object to reflect the light in the water in that depth, but this effect (spotting optic effect) is clearly visible on the sand bed although is not even as intense of the shallower water.
To start, we’re talking performance. Performance does not appeal to probability; that most aquarists are happy with their Discoma ground cover. Kidding, but rationalizing intensity drop off? They later go on suggesting that some corals have not been successful under LEDs due to high and low intensity spotting due to LED optics. It is with these later parts I disagree with in experience and in their calculations.
Behzad and Schneider raise some valid points regarding light refraction in an aquarium test setting, or a static lab state. However, that math gets changed when the aquarium is filled with live animals and moving water. See the issue with light refraction and both internal and external reflection, is that the interface, or water surface is constantly changing.
Overall I find this example and the provided calculations less applicable than one would think. Show me some water surface data sets, run them through some monte carlo algos and then we can actually attempt to quantify the effect. While this is easier said than done, their “attack” on optics needs much more support.
For your application, which side of the LED fence are you on: Optics or Bare Emitters?
